The invention relates to a torsional vibration damper for a shaft rotating about an axis. An apparatus of this general type has a hub element joined to the shaft, and at least two inertial masses, pivotable about pivot axes, that are joined by tension elements to the hub element. The pivot axes of the inertial masses extend parallel to the shaft axis, and are arranged between the inertial masses and the shaft axis so that a change in the distance between the inertial masses and the shaft axis occurs whenever a pivot motion occurs.
A torsional vibration damper of this general type is known. It is utilized on the crankshaft of an internal combustion engine and is based on the recognition that centrifugal (or centripetal) forces cause the inertial masses to circle around the axis at the greatest possible distance when a rotary movement is introduced. The masses are mounted on pivot axes that are arranged in the intermediate zone between their center of gravity and the main shaft axis. Torsional vibrations that are superimposed on the rotary motions consequently result in a relative movement of the inertial masses radially inwardly, which has the effect of dampening the excitational torsional vibrations. The efficiency achieved by such devices is not entirely satisfactory. In addition, clattering noises may occur with the use of such a device during the startup and coasting phase of the internal combustion engine.
There remains a need to further develop this type of a torsional vibration damper so as to produce an improvement in damping efficiency over a wide frequency range, while reliably eliminating clattering noises in the startup and coasting phases of engine use.